std::chrono...::time_point(3)

okay bestie, welcome to std::chrono...::time_point(3) from the C++ Standard Libary manual — yes, the manual name is folded in right here, and we are keeping the typo iconic. 💖

💖 NAME 💖

std::chrono::time_point::time_point — that's the constructor, and its name is literally std::chrono::time_point::time_point, repeated like a queen. 👑

🦋 Synopsis 🦋

the synopsis, with all the (since C++11) and (constexpr since C++14) receipts:

time_point();                                         (1) (since C++11) (constexpr since C++14)
explicit time_point( const duration& d );             (2) (since C++11) (constexpr since C++14)
template< class Duration2 >
time_point( const time_point<Clock, Duration2>& t );  (3) (since C++11) (constexpr since C++14)

Constructs a new time_point from one of several optional data sources. ✨

1. Default constructor — creates a time_point representing the Clock's epoch (i.e., time_since_epoch() is zero). 🕰️
2. Constructs a time_point at Clock's epoch plus d. ➕
3. Constructs a time_point by converting t to duration. This constructor only participates in overload resolution if Duration2 is implicitly convertible to duration. 🧚

🌸 Parameters 🌸

• d — a duration to copy from. 💫
• t — a time_point to convert from. 🦋

✨ Example ✨

the page literally says // Run this code, so here's the whole thing, bestie — no cap:

#include <chrono>
#include <iostream>

using Clock = std::chrono::steady_clock;
using TimePoint = std::chrono::time_point<Clock>;

void print_ms(const TimePoint& point)
{
    using Ms = std::chrono::milliseconds;
    const Clock::duration since_epoch = point.time_since_epoch();
    std::cout << std::chrono::duration_cast<Ms>(since_epoch) << '\n';
}

int main()
{
    const TimePoint default_value = TimePoint(); // (1)
    print_ms(default_value); // 0ms

    const Clock::duration duration_4_seconds = std::chrono::seconds(4);
    const TimePoint time_point_4_seconds(duration_4_seconds); // (2)
    // 4 seconds from start of epoch
    print_ms(time_point_4_seconds); // 4000ms

    const TimePoint time_point_now = Clock::now(); // (3)
    print_ms(time_point_now); // 212178842ms
}

🌈 Possible output: 🌈

0ms
4000ms
212178842ms

💅 See also 💅

• constructor — constructs new duration (public member function of std::chrono::duration<Rep,Period>). 🎀
• duration_cast — converts a duration to another, with a different tick interval (C++11) (function template). ⭐

mwah 💋 — source/version: http://cppreference.com, date: 2024.06.10, and yeah, this was std::chrono...::time_point(3). 🫶